Acquisition - Additional Information (Detail) - USD ($) $ in Thousands, shares in Millions		9 Months Ended		12 Months Ended
	Nov. 14, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Aggregate purchase price		$ 13,600
Deferred payments of previous acquisitions		3,400
Aggregate purchase price		$ 17,021	$ 261,919	$ 3,670,000
Cash acquired				$ 165,800
Issuance of new debt in acquisition	$ 2,400,000
Comdata Inc. [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 3,400,000
Business acquisition date	Nov. 14, 2014
Ceridian LLC [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Common shares issued to finance acquisition	7.6